Comparison of Hydrocarbon-Degrading Consortia from Surface and Deep Waters of the Eastern Mediterranean Sea: Characterization and Degradation Potential

Abstract

The diversity and degradation capacity of hydrocarbon-degrading consortia from surface and deep waters of the Eastern Mediterranean Sea were studied in time-series experiments. Microcosms were set up in ONR7a medium at in situ temperatures of 25 °C and 14 °C for the Surface and Deep consortia, respectively, and crude oil as the sole source of carbon. The Deep consortium was additionally investigated at 25 °C to allow the direct comparison of the degradation rates to the Surface consortium. In total, ~50% of the alkanes and ~15% of the polycyclic aromatic hydrocarbons were degraded in all treatments by Day 24. Approximately ~95% of the total biodegradation by the Deep consortium took place within 6 days regardless of temperature, whereas comparable levels of degradation were reached on Day 12 by the Surface consortium. Both consortia were dominated by well-known hydrocarbon-degrading taxa. Temperature played a significant role in shaping the Deep consortia communities with Pseudomonas and Pseudoalteromonas dominating at 25 °C and Alcanivorax at 14 °C. Overall, the Deep consortium showed a higher efficiency for hydrocarbon degradation within the first week following contamination, which is critical in the case of oil spills, and thus merits further investigation for its exploitation in bioremediation technologies tailored to the Eastern Mediterranean Sea.

Diversity and Hydrocarbon-Degrading Potential of Deep-Sea Microbial Community from the Mid-Atlantic Ridge, South of the Azores (North Atlantic Ocean)

“…Indeed, prior exposure of the inoculum to the pollutant caused an adaptation of the microorganisms to utilize the hydrocarbons as carbon and energy sources, shortening the lag phase and accelerating the beginning of the exponential phase [57]. Furthermore, Charalampous et al [58] in a recent work reported differences in hydrocarbons removal between shallow and deep sediment consortia (50-58% and 33-42%, respectively), highlighting the role of consortium origin.…”

Emulating Deep-Sea Bioremediation: Oil Plume Degradation by Undisturbed Deep-Sea Microbial Communities Using a High-Pressure Sampling and Experimentation System

“…We developed and successfully employed a high-pressure apparatus for sampling and experimentation with seawater that was collected from depths down to 1000 m, without any pressure disruptions during sample retrieval and with an uninterrupted pressure flow between each step. Our previous work with enriched consortia from the deep waters of EMS [44] showed their capability for effective crude oil bioremediation in the case of an oil spill. Following this work and focusing on a real-life scenario of a deepsea oil release where oil is entrapped in plumes, we successfully proved that indigenous microbial populations from EMS are readily available to combat subsea oil spills.…”

“…EMS faces new challenges, as existing oil and gas reserves in the area, along with the intensification of offshore oil and gas exploration activities in deep and ultra-deep waters, pose a threat for an accidental oil release in the deep-sea environment. Our current knowledge on microbial response in the deep EMS is still very limited [42][43][44] and the so-far available biodegradation rates derive from our previous work on enriched deep-water consortia that are grown at atmospheric pressure [44]. EMS consortia that were collected from surface and deep waters in our previous work showed that the latter resulted in a higher efficiency for hydrocarbon degradation within the first week following oil contamination [44].…”

“…Our current knowledge on microbial response in the deep EMS is still very limited [42][43][44] and the so-far available biodegradation rates derive from our previous work on enriched deep-water consortia that are grown at atmospheric pressure [44]. EMS consortia that were collected from surface and deep waters in our previous work showed that the latter resulted in a higher efficiency for hydrocarbon degradation within the first week following oil contamination [44]. In this study, we aim to investigate the microbial degradation of crude oil in the deep EMS under in situ conditions.…”

Distinct communities of Bacteria and unicellular eukaryotes in the different water masses of Cretan Passage water column (Eastern Mediterranean Sea)

“…The method followed for DNA extraction has been previously described in Charalampous et al [26]. In summary, membrane filters were vortexed in CTAB extraction buffer, followed by three freeze-thaw cycles.…”